Brumbies coach Jake White has sent a formal request to Japanese rugby union club Suntory seeking to extend the loan of star flanker George Smith.

Smith's current short-term deal is due to end after the Brumbies take on the Hurricanes on May 31 but the Canberra-based Super Rugby franchise is seeking to prolong his stay in the wake of Wallabies flanker David Pocock's season-ending knee injury and Smith's outstanding form in his place.

White sent his request to Suntory on Tuesday night and but has stressed that, while he'd been encouraged by talks with Suntory coaches last week, the decision still rested with the Japanese club's top officials.

"I've just formally given them some options of how we think time frames could work," White said. "It's just giving them alternatives of how many weeks we would want him - best case, worst case and which one they would look at. And they might for argument's sake say: 'listen no problem, you can have him right to the end', because their season only starts on (August 18) anyway."

At present, the June 7 clash with the Melbourne Rebels and then the July 13 match against the Western Force are the only fixtures Smith is set to miss for the Brumbies before the finals from July 19 to August 3.

Should Suntory grant an extension, Wallabies coach Robbie Deans would likely want the option of recalling him to national duty for the three-Test series against the British & Irish Lions.

But that would mean the Australian Rugby Union would need to create a precedent in picking an overseas-contracted player.